Objectives Evaluate the level of dietary calcium required for an adult rhesus monkey and determine if the presence of lead stored in bones has an effect on mobilization of Ca from bone. ABSTRACT:There is widespread concern that a large percentage of the human geriatric population does not meet their daily dietary calcium requirement and can therefore suffer from many bone diseases including osteoporosis. To complicate this problem even further, many of the elderly grew up in a time when lead (Pb) was widely used in many products (i.e. gas and paint) and they therefore had a large potential for exposure. The skeletal system is the site of long-term storage of lead. When an older person does not meet their dietary intake of calcium they have the potential to mobilize lead from the bone as they mobilize calcium. We are evaluating these issues in geriatric female monkeys to determine what effects previous exposure to lead may have on mobilization and reformation of bone. Key Words Lead, Monkeys, Diet, Calcium requirement, PTH, osteocalcin